Engine cooling systems generally include a thermostat for regulating coolant flow between an engine and a radiator based on one or more engine parameters, such as, engine speed, coolant temperature, etc. Thermostat failure may result in irregular coolant flow between the engine and the radiator, which may cause excessive heating or excessive cooling of the engine.
Usually, thermostat failure is detected by monitoring temperature of the coolant flowing between the engine and the radiator. However, monitoring coolant temperature in warm and hot ambient conditions may not accurately detect thermostat failure.
U.S. Pat. No. 9,217,689 (hereinafter referred to as the '689 patent) relates to methods and systems for diagnosing each of a plurality of engine cooling components including various valves and grill shutters. Each valve may be individually closed and opened for a specified duration, and corresponding changes in coolant temperature are monitored. If all the components are functional, the various valves are adjusted to stagnate coolant at the engine and expedite engine warm-up during a cold start. However, '689 patent also uses coolant temperature to diagnose valves in the engine cooling system.